Process for making high stretch and elastic knitted fabrics from polytrimethylene terephthalate

Abstract

This invention relates to a process of making high stretch elastic knitted fabrics from (PTT) which comprises:(a) making a drawn textured yarn with an elongation to break of 30 to 60 percent by:(i) spinning a polytrimethylene terephthalate polymer into a partially oriented yarn, and(ii) draw texturing the yarn in a false-twisting texturing machine at a draw ratio of 1.05 to 2.0, and a yarn temperature of 50 to 200° C. using a either a contact heater or a non-contact heater, and(b) knitting the yarn into a fabric composed of intermeshing loops of the yarn wherein the stitch length is from 22 cm/100 stitches to 26 cm/100 stitches, and(c) scouring the knitted fabric, and(d) drying the fabric on a belt, and(e) dyeing the knitted fabric at atmospheric pressure by dispersing a dye and the fabric in water and increasing the temperature, and(f) finishing the dyed knitted fabric according to the specific procedure and(g) drying the fabric on a belt.

We claim:  
     
       1. A process of making a high stretch elastic knitted fabric from polytrimethylene terephthalate which comprises: 
       (a) making a drawn textured yarn with an elongation to break of 30 to 60 percent by combining the steps of:  
       (i) spinning a polytrimethylene terephthalate polymer into a partially oriented yarn, and  
       (ii) draw texturing the yarn in a false-twisting texturing machine at a draw ratio of 1.05 to 2.0 and a yarn temperature of 50° C. to 200° C., and  
       (b) knitting the yarn into a fabric composed of intermeshing loops of the yarn wherein the stitch length is from 22 cm/100 stitches to 26 cm/100 stitches, and  
       (c) scouring the knitted fabric according to the following procedure:  
       (i) load the fabric into a dyer with water at 30 to 40° C. for 12 to 15 minutes, and  
       (ii) add 0.5 to 1.5% on weight of fabric of spin finish remover, and  
       (iii) raise the temperature to 100° C. at a rate of 1.0 to 2.5° C., and  
       (iv) hold for 5 to 10 minutes, and  
       (d) drying the fabric:  
       (i) on a belt at a speed 13 to 23 meter/minute through a forced air oven at a temperature of 88 to 98° C. with a residence time of 52 to 62 seconds, or  
       (ii) on a belt at a speed 13 to 23 meter/minute through a tenter frame forced air oven at a temperature of 135 to 145° C. with a residence time of 52 to 62 seconds, and  
       (e) dyeing the knitted fabric at atmospheric pressure by dispersing a dye and the fabric in water and increasing the temperature according to the following procedure:  
       (i) preheating the fabric to a temperature of from 25° C. to an upper limit of 44 to 54° C. by increasing the temperature at a rate of 1.0° C. to 2.5° C. per minute, and  
       (ii) adding the dye chemicals to the fabric in water, and  
       (iii) preheating the fabric to a temperature of from 44 to 54° C. to 55 to 65° C. by increasing the temperature at a rate of 1.0° C. to 2.5° C. per minute, and  
       (iv) preheating the fabric to a temperature of from 55 to 65° C. to 105 to 115° C. by increasing the temperature at a rate of 1 to 2° C. per minute, and  
       (v) maintaining the dyeing solution at this temperature for from 30 to 50 minutes, and  
       (f) finishing the dyed knitted fabric according to the following procedure:  
       (i) cooling the dyed knitted fabric to 82 to 98° C. at a cooling rate of 1° C. to 2° C. per minute, and  
       (ii) adding reduction agent(s) for scouring which is carried out for from 3 to 7 minutes, and  
       (iii) cooling the dyed knitted fabric to 55 to 65° C. at a cooling rate of 1.0° C. to 2.5° C. per minute, and  
       (iv) washing the dyed knitted fabric with room temperature water for from 10 to 20 minutes, and  
       (v) adding a solution of 0.25 to 0.75 weight percent weak organic acid, and  
       (vi) heating the dyed knitted fabric to 44 to 54° C. at a rate of 1.0 to 2.5° C. per minute and holding it at that temperature for from 5 to 15 minutes, and  
       (vii) washing the dyed knitted fabric at 34 to 44° C. for 5 to 10 minutes, and  
       (viii) removing the fabric, and  
       (g) drying the fabric:  
       (i) on a belt at a speed of 13 to 23 meter/minute through a forced air oven at a temperature of 88 to 98° C. with a residence time of 52 to 62 seconds, or  
       (ii) on a belt at a speed of 13 to 23 meter/minute through a tenter frame forced air oven at a temperature of 135 to 145° C. with a residence time of 52 to 62 seconds.  
     
     
       2. The process of  claim 1  wherein the yarn is made with an elongation to break of 35 to 55 percent and the draw texturing in step (a) (ii) is carried out a draw ratio of 1.15 to 1.5 and a yarn temperature of 130° C. to 180° C. 
     
     
       3. The process of  claim 1  wherein the stitch length in step (b) is from 23 to 25.5 cm/100 stitches.